Kevin Costner Marries Girlfriend in Aspen

Kevin Costner married handbag designer Christine Baumgartner in a ceremony at the actor-director's 165-acre ranch outside Aspen, Colo., on Saturday.

Costner, 49, pulled up to the ceremony site in a horse-drawn carriage, and Baumgartner, 30, arrived soon after in a vintage green pickup truck. The pair tied the knot by a stream, then celebrated with their guests under a tent nearby. Celebrity guests included Tim Allen, Don Johnson and Costner's Dances with Wolves costar Mary McDonnell. It's the second marriage for Costner, the first for Baumgartner.

Costner, who has three children with his first wife, Cindy Silva (Anne, 20, Lily, 18, and Joe, 16), briefly met Baumgartner while golfing more than a decade ago, but didn't begin dating her until they met again at a restaurant in 1998. (Costner and Silva split in 1994.) "We exchanged numbers, and I told her that I would – did she mind if I called her in two weeks. I did not realize that was like an insult to a woman," Costner told PEOPLE in 2003.

Despite a brief split in 2002 and an almost 20-year age difference, the two are "like little kids together, really in love," said close friend David Giammarco.